[OSRM-talk] "nearest suitable road segment" Was: Helgoland in St. Peter-Ording

Daniel Patterson daniel at mapbox.com
Wed Aug 17 21:26:22 UTC 2016


Florian,

  Some of us have discussed what it might looks like to consider the "walking segment" as part of the shortest calculation - i.e. change the routing algorithm to:

    - consider all possible start points within 100m of the start coordinate (maybe 1m increments along the road)
    - consider all possible end points within 100m of the end coordinate
    - find the fastest routes between all points
    - calculate the "walking duration" from the start coordinate to the snapped start point
    - calculate the "walking duration" from the end coordinate to the snapped end point
    - select the shortest route after adding the walking durations to the road durations

  There are a few situations when dropping markers near major highways where this approach could improve snapping behavior.

  This makes routing quite a bit more expensive and complex, but might have some of the effect you're looking for - considering the distance from your coordinate to the actual routing graph.  Nobody has written code to do this yet though, but it might be worth exploring a bit.

  I'm not sure it would help with the Münsterstraße 15a example - in that case, what we really need are street address coordinates along Münsterstraße itself, rather than building centroids.  This is pure geocoding, I don't know what OSRM could do to help.  Perhaps you need to create a custom geocoder that snaps building centroids to nearby roads with the same name as they have in their `addr:*` tags?

daniel

> On Aug 17, 2016, at 2:00 PM, Florian Lohoff <f at zz.de> wrote:
> 
> In my primary mapping area we decided to avoid "area style POIs"
> whenever possible for exactly this reason. Building a centroid on
> an area and routing to the nearest point on the routeable network
> is most of the time not the right answer. You dont want to end up
> in the middle of a multi-acre campsite - you want to be sent to the
> reception.
> 
> Flo
> -- 
> Florian Lohoff                                                 f at zz.de <mailto:f at zz.de>
>             UTF-8 Test: The 🐈 ran after a 🐁, but the 🐁 ran away
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